The response to irradiation of several different slowly-responding tissues will be studied with particular reference to the effect of dose fractionation but also as they relate to other insults, particularly surgery or an inflammatory response mimicking that after surgery. The tissues (and effects of interest) include the peritoneum (adhesion formation), dermal fibrovasculature (wound healing), liver (hepatocyte survival) and lung (pneumonitis). The animals used will be specific pathogen free mice. In parallel with quantitation of the dose fractionation response and of the time course of the various tissue effects, an effort will be made to elucidate the mechanisms underlying the responses. The purpose of the experiments is to understanding the biology of normal tissue responses to irradiation and to use that knowledge to improve both radiotherapy and multidisciplinary approaches in cancer treatment.